Iverntech MGN12H 450mm Linear Rail Guide with 2 Stainless Steel Carriage Blocks for 3D Printer and CNC Machine

I have torn my primary 3D printer down to replace the rails. These are not the cheapest rails available but they are certainly economical. They are very rough and packed with shipping grease from the factory. At first I thought they would be unusable.Begin by spraying the entire rail and block assy with Brake Cleaner. This will get most of the gunk off. Then remove one of the red retainer buttons, hold the rail upside down, and over a towel or thick rag, carefully slide the Carriage Block off. I would then spray the bearings and block again with Brake Cleaner. At this point you have a choice - go with the original ball bearing or swap them for better quality. I ordered two sets of https://www.amazon.com/gp/product/B015RKOZ7G/ref=ppx_yo_dt_b_asin_title_o07_s00?ie=UTF8&psc=1precision ball bearings. I took out the originals and replaced them with the SAME NUMBER of the replacement balls.I then sprayed the inside of the block with Super Lube 31110 (Spray) and worked the balls round the track. The then put a small amount of Super Lube 92003 Silicone Lubricating Grease on the balls and track. (Believe me, the 3 oz tube will last for years!) I sprayed the rails with the Super Lube spray and wiped them down with a clean cloth. Then I reassembled the block onto the rail. Swipe the block back and forth and it should be a smooth as can be.Please click the "Helpful" button below

ordered 2 for my 3d printer. one barely moved at all, even when vertical. the other moved and would stick in the middle then move again if you shook it. I was less than enthused.the consensus across the internet was "you get what you pay for" and "cheap Chinese rails wont ever work". still, I didn't want to just give up and return them without trying to see if I could fix them. I tried spraying them with liquid wrench spray lubrication, it helped very very little. I watched a video where someone took apart the rails, soaked them in a solution of alcohol and water, put them back together, and re-greased them. The claim here was that they were "gunked up" from the factory and needed to have better lubricant applied. I tried this and then applied "super lube". This did not work.Finally I found a video of some random kid on youtube. He replace the bearings with https://www.amazon.com/dp/B015RKOZ7G/ and also claimed this changed his barely movable rails to smoothly functioning ones. I was fresh off of watching the previous video about cleaning, and since that had failed, I was skeptical of this, but they were $8, so I figured why not. I just completed the first rail, applied some "super lube", and it now moves with the slightest tilt of one side or the other. (note: if you do this, the part I mentioned above comes with 100 bearings, each side of the carriage needs 33, and there will be a slight gap left over).so, why 3 stars? whats the bottom line? the bottom line is the consensus on the internet is largely correct. there isn't really a middle ground with rails. there's expensive ones that work really really well and come ready to go, and everything else is pretty bad. these however, are super cheap, and can be remedied for not much more of an investment. $8, some patience, a clean, and re-lubrication, and you've got a solid linear rail. if you want a cheap, good solution (albeit with some work involved), these are for you. if you want an out of box solution, be prepared to pay much more.

These rails really perform pretty amazingly right out of the box. Unlike a lot of the cheaper Hiwin replicas out there, these came nicely oiled and sliding smoothly instead of covered in shipping wax and dragging.That being said, I still did my standard practice of disassembling the rails, cleaning with isopropyl alcohol and re-lubricating with Slick50 Supercharged One Lube and MAN are these things smooth now!While I had them apart, I noticed a few small details that I think are major contributors to these rails performing better than most. First, the quality of the molded plastic parts is much better than expected. There is no flash on any of the edges and they all fit together nicely. Second, and maybe more importantly, the start and end of the tracks that the balls actually roll in have been carefully relieved and tapered so that when the balls enter and exit the tracks there is no hard edge to roll ever and cause any clicking or dragging.These rails are FAR better quality than the offerings of RobotDigg and blow v-slot wheels rolling in 2020 aluminum extrusions out of the water. In my case, an Ultibots D300VS+ delta printer, the swap from v-slot wheels to these linear bearings cause the result of a vase mode test print to go from the ripply appearance of the blue part pictured to the buttery smooth appearance of the black part using the same g-code!Long story short, these are pretty great rails in my experience. Give them a shot!

I used this on my Tevo Tarantula for the X axis. I had some trouble because I looked at the holes in the rail and thought they used the same M4 screw and T nut system that the rest of the Tarantula and virtually all 2020 and 2040 extrusions use. Plus, I saw no mention of any difference in the product info. So, I tried to get a M4 to fit and it looked a little tight. I decided to try my brand new drill press out. I set it to 650 rpm, and tried to drill the holes out a bit. Boy is my wife mad! This rail is built from such incredibly hard steel that a drill bit exploded and sent shrapnel into my right arm! I went through 3 more bits before I gave up after only 1 inner hole was cleared. Wow, talk about tough steel. Slides nice, too. Despite being injured I would still recommend these but I will mention that they should advertise that they are supposed to use M3 bolts and T nuts, NOT the normal M4s. Going to save up my courage to see if the wife will look past the injury to allow the $60 to buy the 2 more 400mm units I need for my Z axis - I might need first aid just asking her LOL.

The rail and block had marks on it like it's been used and there was a 0.08mm bow to it. Otherwise it slides smoothly

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